Conveyor

ABSTRACT

A reciprocating bar conveyor having a plurality of parallel eccentrically supported bars angularly spaced from each other and grouped into at least two sets. Each set may be angularly spaced from each other set, and each set includes at least six bars which are individually angularly spaced from each other bar of the set. Each set of bars is supported on a pair of eccentric axles, only one of which need be connected to a drive motor.

United States Patent Paul, Jr. Feb. 5, 1974 CONVEYOR [75] Inventor:Dwight D. Paul, Jr., Mount Pmfwry Exam ler EVn Blunk Clemens MichAssistant Exammer.l0seph E. Valenza Attorney, Agent, or Firm-Burton &Parker [73] Assignee: M. S. C. Inc., Mount Clemens,

Mich.

[22] Filed: Nov. 18, 1971 [57] ABSTRACT [21] Appl. No.: 200,010

A reciprocating bar conveyor having a plurality of [52] CL I 198/219parallel eccentrically supported bars angularly spaced [51] Int. CL25/04 from each other and g p into at least two sets. 58] Field ofSearch 198/219 Each set may be angularly spaced from each other set,

i and each set includes at least six bars which are indi- {561References Cited vidually angularly spaced from each other bar of theset. Each set of bars is supported on a pair of eccen- UNITED STATESPATENTS tric axles, only one of which need be connected to a 2,791,3385/1957 Thaon De Saint-Andre 198/219 drive mot 1,367,061 2/1921 Lewis198/219 FOREIGN PATENTS OR APPLICATIONS 5 Claims, 10 Drawing Fi 366,2932/l932 Great Britain l98/2l9 r "'"I JH J 2 36 a l 72 74 7 a 78 80 a 7/73 6 2 77 7.9 J 2 l 'T. "1LT" PAIENTEB FEB sum 1 or 2 fl UTh.

5 x T R WW m m @m m M WV 6 CONVEYOR BACKGROUND OF THE INVENTION.

In reciprocating bar conveyors of the type shown in U. S. Pat. No.2,791,338, the efficiency of the conveyor suffers from utilizing asubstantial portion of the driving power in simply lifting the loadbeing conveyed. In addition, the vertical velocity of the load causesundesirable vibration and chatter on the conveyor, and horizontalvelocity is relatively low in relation to the power input. Also, I havefound that in a conveyor of the type disclosed in said patent, each axlewhich eccentrically supports the conveying bars, must be poweredotherwise the conveyor will not function or will not function properly.

SUMMARY OF THE INVENTION Objects of this invention are substantiallyincrease efficiency of reciprocating bar conveyors; drive the conveyorby connecting the power train to only one axle of each set of bars;obtain for a given power input a greater horizontal velocity and a lowervertical velocity than in the prior art; increase the allowable weightof articles which may be conveyed using a lesser power input than in theprior art; provide a simpler construction; and reduce cost.

I have discovered these and other objectives may be obtained byproviding a conveyor with at least two sets of bars for cooperativelysupporting the articles to be conveyed with each set comprising at leastsix bars and with each bar of a set angularly spaced from each other barof the set. Other features will become apparent from the followingdescription.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational viewalong the length of a conveyor;

FIG. 2 is an end view, partly in section, along the line ll-II of FIG.3;

FIG. 3 is a fractional top view of the end of the conveyor;

FIG. 4 is a detail of an axle showing the modular eccentric arrangement;

FIG. 5 is a schematic plan of the relationships between the number ofbars and the efficiency of a step;

FIG. 6 is a schematic plan of several different steps;

FIG. 7 is a planar view of a driving axle showing a phasing sleevebetween sets of bars;

FIGS. 7a and 7b show the phasing arrangement provided for by FIG. 7; and

FIG. 8 is an expanded view showing the relationship of all theeccentrics within one set of six bars.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring moreparticularly to the drawings, reference numeral 10 indicates a set ofsupporting bars while 12 indicates any single supporting bar.

As shown in side elevation in FIG. 1, and end elevation in FIG. 2, aframe 14 comprising upright members 16, braces 18, and cross members and22, support two parallel, spaced beams 26 in which axles 30 arejournalled and bearing mounted in a conventional manner. The embodimentshown in FIGS. 1, 2 and 3 includes a pair of guide rails 28 to preventany sideward movement of the articles 38 being conveyed. The axles 30are spaced apart from one another over the length of the conveyor sothat the sets of bars and the articles carried are adequately supportedwithout appreciable bending of each of the bars 13 as they sequentiallysupport the objects carried.

In the embodiment shown in FIG. 4, each bar 12 is formed from one ormore beams and annular connection members 102. The beams 100 are madefrom rectangular bar stock having width 54 and thickness 56 and madefrom structural materials such as steel or aluminum. The beams have ahalf semicircular recess 104 at each end 108 so that when connected tothe annular connecting member 102, they will form a flat continuoussurface 106 from beam to beam across their ends 108, also their sideswill form a flat surface so that bars 12 can be closely positionedtogether without interferring with each other. Dowell pins 110 and bolts112 secure each beam 100 to the annular members 102 to provide a rigidcontinuous bar 12 of the desired length. The ends 108 may leave a smallgap between beams to facilitate assembly. If desired, a strip of hard,wearresistant material (not shown) may be attached to the top surface106 to reduce wear, eliminate any gaps at 108, and further rigidify thebar.

The annular connection members 102 are made from structural material andhave flanges 114 to provide secure mountings for the beams 100. Theconnection members 102 have the same thickness 56 as do the beams 100 sothat the bars 12 have a uniform thickness. The interior diameter of theannular member is sized so that a bearing 34 will press fit securelyinto this diameter. The bearing 34 is in turn press fit around acircular eccentric disc 32 which is to be securely mounted on the axle30. The bearing 34 has the same thickness as or slightly lesser than thebar 12.

The eccentric disc 32 has the center 44 of its external radius offsetfrom the center 46 of the aperature 35 through which the axle 30 passes.The eccentric disc also is provided with holes 116 and 118, bothequidistant and angularly spaced from the center of the axle aperture 46according to the number of bars 12 in each set 10. For example, if thereare 6 bars in a set, the holes 116 and 118 will be spaced 60 apart. Itwill be noted that the center 44 of the eccentric disc 32 falls on theline between hole 116 and the center 46 of the aperture 35. Hole 116 issized to receive the head of a small bolt and 118 is threaded to securethe corresponding bolt on the adjacent eccentric. In this manner,eccentric discs 32 on adjacent bars 12 can be securely fastener togetherto form a solid unit having substantial strength on the axle 30. Thedistance between centers 44 and 46 determines the eccentricity andforward motion of the conveyor as described below.

In order to provide clearance between the relatively moving parts ofadjacent bars 12, the discs 32 may be made slightly thicker than thebars 12. The apertures 35, if the axle 30 is non-round, must be orientedso that proper angular spacing will occur between adjacent bars 12. Ihave found this to be most conveniently done by either bisecting a sideof the aperture 35 with a radius through the center 44 of the disc as inFIG. 4, or

aligning the vertices of the aperture 35 with a radius 100 theappropriate distance from the end of the bar 12.

If the bar 12 is composed of only a single beam 100, it may be moreconvenient to avoid the use of annular connecting members entirely andincorporate a circular aperture in the beam 100 to receive thebearingdisc-axle combination directly within the beam. This arrangementis shown by the bars in FIG. 2.

Two groups or sets of bars 12 are employed with a separation between thesets on the axle 30 so that the articles 38 are supported on both sidesof their centers of mass 39. However, many sets of bars 10 may beemployed if needed to provide more continuous lateral support for thearticles conveyed.

When two groups 10 of bars 12 are employed, it is usually desirable thatthere be an angular spacing between the sets so that optimum efficiencywill be achieved. This angular spacing effectively doubles the number ofbars that pull through the non-driving axles if unitary axles are used,thus providing a smoother transfer of power to the non-powered axles.This angular spacing can be achieved through use of eccentric discs 32having their apertures aligned in the two ways described above andmounted on a unitary axle of polygonal bar stock. In this case mountingcollars 36 in FIG. 2 enable the axles to rotate freely in the supportingbeams 26. However, a preferable method of obtaining angular spacingbetween sets is by the use of a compound axle 130 as shown in FIG. 7.Since this angular spacing between the sets need only be applied throughone common axle, the remaining axles can be independently mounted foreach set if it is not desired to use compound axles throughout.

The compound axle 130 is composed of three parts: polygonal portions 132for supporting each set of eccentrics, cylindrical portions 134 formounting the axle in the frame 26, and a cylindrical sleeve portion 136for connecting the two polygonal portions. The cylindrical mountingportions 134 are preferably made by machining the end of a solid lengthof polygonal bar stock, such as hexagonal or octagonal, thus forming thepolygonal portion 132 and the mounting portion 134 from a solid piece ofmaterial. The length of the sleeve 136, and consequent spacing of thesets 10 of bars will depend upon the use of the conveyor. The sleeve 136has its interior machined at each end so that each polygonal portion 132will be press fitted into fixed angular relationship with each other.For example, as shown in FIGS. 7a and 7b, hexagonal portions, since theyhave faces 60 apart, will be offset 30 from each other. Also shown inthe sleeve 136 are keyways 138 to hold dogs 140 which are used forsecuring the set of eccentrics to the axle 130. The dog 140 fits overthe end of the sleeve 136 and has a hole 142 positioned so that a boltcan connect with the threaded hole 118 of the first eccentric 32 in theset. The dog is provided with a key 142 so that a large amount of torquecan be applied to the axle. Provision can be made in the sleeve 136 alsofor a drive sprocket 58 and its keyway 146.

The driving sprocket may be internal, as shown in FIG. 7 or may be on anextension of the driving shaft 30 passing through the supporting beam26, as shown in FIG. 2. A chain or belt 60 then connects to the motor 64through a gear reduction unit 62 as shown in FIG. 1. The motor 64 andgear reduction unit 62 are mounted on the frame 14 by brackets 70 and 24so that a constant tension slackless drive is maintained.

Since only one axle need be coupled to all sets of bars, the remainingsupporting axles 30 can be independent for each set 10 of bars. Thesupporting axles can be conveniently made by machining a length ofpolygonal bar stock at each end and joumalling these into the frame. Itis most efficient if the coupling axle is also the driving axle sincethen the power is evenly applied to both sets of bars.

The order of positioning of the bars within each set is unimportant solong as the minimum spacing between sets is sufficient to provide stablesupport for the article carried. In the example of FIG. 2, the minimumspacing occurs when bars 71 and 82 are the supporting pair of bars.

The phase relationship between the bars should be uniform to provide asmooth ride reducing vibration to a minimum. However, it is possible touse any phase sequencing between the bars even though loss of efficiencywill result. The phase relationship between sets also should be uniformto provide maximum efficiency. FIG. 8 shows one set of eccentricsseparated and numbered 71" to 76" to show the phasing between theindividual bars 71 to 76 as in FIG. 2. In this case since six bars areused, each eccentric is one-sixth of a complete cycle from the adjoiningeccentrics or 60.

The solid lines of FIG. 6 show the path of one side of an articleconveyed by one set of evenly spaced bars. The dashed line in FIG. 6 isthe path of the other side of the article supported by the other set.Due to the offset positioning, it is obvious that the article conveyedwill rock back and forth as it proceeds along the conveyor similar tothe waddle of a duck.

To illustrate the operation through one cycle, the two sets of six barsin FIG. 2 are individually numbered from 71 to 82 respectively, and thecorresponding primed reference numbers 71 to 82' in FIG. 6 indicate theinterval during which each bar is supporting the article carried.Suppose bars 71 and 77 in FIG. 2 are instantaneously supporting thearticle conveyed, as pictorially shown in FIG. 6 by the interval 83. Inthe interval 83, bar 77 is descending in its arc while bar 71 is risingas shown by 77' and 71 respectively. At point 84, bars 77 and 82 areboth instantaneously supporting the article on one side as 77 falls and82 rises. At this point, the support shifts from 77 to 82. Also at point84, bar 71 is at the highest point of its trajectory and after thisbegins its fall. During the interval 85, bars 82 and 71 support thearticle. At the end of interval 85, bar 71 has fallen to an equal pointwith rising bar 76. At this point, 86, the support of the article in theright set shifts from bar 71 to bar 76. Simultaneously at point 86, bar82 reaches its highest point and begins to decline. This processcontinues with the article supported in turn by pairs of bars with'onebar of each pair replaced at a time. Thus the supporting pairs of barsthrough one cycle in sequence are: (71, 77), (71, 82), (76, 82), (76,81), (75, 81), (75, (74, 80), (74, 79), (73, 79) (73, 78), (72, 78), and(72, 77) which leads back to the starting pair (71, 77).

If the operation of the motor is reversed, the conveyor will transportthe articles in the reverse direction and the bars will move in thereverse sequence.

FIG. 5 shows schematically the factors involved in determining the ratioof forward carry to rise-and-fall of the article conveyed. The radius 91is the distance between the axis of the axle 46 and the axis of theeccentric disc 44. The radius 91, which is the degree of eccentricity ofthe bars, does not affect the ratio of the height 93 through which thearticle 38 rises and falls to the distance traversed 92 by the articlewhile supported by one bar. This ratio depends solely on the angle 90and the angle 90 is determined solely by the number of bars in a set ifuniform spacing is provided. For six bars, angle 90 is 60; for eightbars, angle 90 is 45, and so forth. As the angle 90 becomes smaller theratio of 92 to 93 becomes larger. The larger this ratio becomes, themore energy is used to transport the article forward and the less iswasted by rise and fall of the article conveyed. Table I gives the ratioof the forward travel 92 to the rise-and-fall 93 and indicates thechange resulting from adding more bars.

TABLE I Number Angle 90 Ratio of of bars 93:92 2 180 2.0:l 3 120 35:1 490 4.8:] 6 60 7.5:] 8 45 10.011 l0 36 12.6:[ l2 30 14.8:!

It will be noted that the saving in energy caused by adding more bars tothe set falls off very rapidly once the set becomes larger than 10 or 12bars.

A counterbalancing consideration to continually increasing this ratio byincreasing the number of bars is the increase of frictional energylosses which occur with the addition of bars within the sets. While theoptimal number of bars will depend upon several design factors listedbelow, there eventually reaches a point where the increase in frictionalenergy loss exceeds the energy gain by addition of more conveying barswithin a set. The factors involved in this tradeoff include the lengthof the conveyor (and consequent number of friction producing axles), theweight of the articles conveyed, the friction properties of the bearingsused, the speed at which the conveyor inn, and the number ofstarts/stops in use of the conveyor. Another obvious factor is the spacethat a set of bars will occupy. For most industrial applications theoptimal number of bars per set ranges between six and 10, while forwarehouse applications the optimum may range up to 16 per set.

It will be obvious to the careful observer that if the center of gravity39 of the objects carried lays along the axis of rotation of the rockingmotion of the sets of bars, then there is no advantage in increasing thenumber of bars in a set beyond three or four becasue there is novertical motion of the center of gravity. However, this is seldom thecase. Even a symmetrical object, as shown in FlG. 2, will have itscenter of gravity rise and fall, which results in consumption of energy,unless it is exactly positioned on the axis of rotation. Consequently, aplurality of bars is needed to optimize practical operation.

Although even numbers of bars have been shown in each set, this is onlyfor convenience in providing exact angular spacing of the sets. An oddnumber of bars is within the contemplation of this invention althoughcare must be taken that the angular spacing is uniform otherwise thewaddling duck motion of the articles conveyed will resemble a waddlingduck doing a cha-cha.

Another factor affecting the number of bars employed in a set is thetype of drive that is used. If it is desired to drive the conveyorthrough only one axle thus avoiding hazardous, expensive and complicateddriving mechanisms, then at least six bars must be employed in a set. Iffewer bars are used in a set, power consumption will be greatlyincreased. This increase in power consumption results from thedifficulty of pulling the bars through a cycle. If the number of bars isnot large enough, the conveyor can actually stall out, particularlyunder heavy loads when used as an accumulating conveyor. The smoothnessof the conveyor operation increases as the number of bars increases.Even six bars has been found to give unsatisfactory operation unless theeccentricity (the distance between centers 44 and 46 in FIG. 4) is largeenough. However, increasing the eccentricity much beyond the radius ofthe axle unduly increases the amount of torque required, and this willnecessitate heavier construction of the bars and axles requiring morecostly materials. This also adds to the weight of the moving parts,requiring larger forces and more power to start the conveyor or reversedirections.

There is no limit to the load that can be carried by this method. Forheavier loads, it is merely necessary to provide more closely spacedaxles or increase the size of the bars. There is likewise no limit onthe length of the conveyor providing that sufficient power is supplied.In cases where the heaviest loads are to be conveyed over longdistances, for example, pallets weighing two and a half tons or more,over a distance of 35 feet, it may be desirable to drive morethan oneaxle to assure adequate performance. This can be done using conventionaltechniques. In the example, a 20 horsepower electric motor will move thepallets at a rate of fifteen feet per minute and accumulate them overthe entire length satisfactorily.

For most applications, however, it is more than adequate if one axle isdriven. For example, a one-quarter horsepower electric motor will haveno problem accumulating pound parts on a four foot conveyor at the rateof 60 feet per minute. In another example, a 0.9 horsepower motor isutilized to convey 460 pound pallets at 50 feet per minute on a 2% footconveyor.

What is claimed is:

.l. A conveyor comprising a pair of parallel sets of parallel articlesupporting and conveying bars with each set comprising at least sixbars, means supporting the bars of each set in angularly spacedeccentric relation with each bar equally angularly spaced from eachother bar of the set for eccentric movement beneath an article restingthereon, said means supporting the bars being arranged to continuouslypresent, during eccentric movement of the bars, a pair of bars with onefrom each set in cooperative article supporting relation on oppositesides of the center of mass of an article supported on the bars, saidmeans for supporting the bars including a pair of regular polygonallyshaped axles disposed spaced apart longitudinally of the bars and eachhaving the same number of faces as the number of bars in each set andwith the number of bar faces being at least six in number, a pluralityof identical bar supporting discs with one for each bar, said discshaving corre sponding off-center polygonal apertures sized to slidablyfit in driven relation on the polygonal axles and with the discsreceived thereon in angularly spaced relation in accordance with theangular spacing of the faces of the axles, each bar mounted on one ofthe discs on each axle to be driven in eccentric movement as aforesaidupon rotation of the axles, and means connected to one of the axles forrotating the same and thereby driving the bars. 1

2. The invention as defined by claim 1 wherein there is a polygonal axlefor each set with the number of sides of the polygon being a function ofthe number of bars in the set, and the axles of the pair of sets are endconnected in angular offset relation equal to one-half the angle betweenthe sides of the polygonal shape of the axles.

3. In a conveyor as defined in claim 1 where the means for driving thebars is connected to both sets of bars.

ing to provide clearance between adjacent bars.

1. A conveyor comprising a pair of parallel sets of parallel articlesupporting and conveying bars with each set comprising at least sixbars, means supporting the bars of each set in angularly spacedeccentric relation with each bar equally angularly spaced from eachother bar of the set for eccentric movement beneath an article restingthereon, said means supporting the bars being arranged to continuouslypresent, during eccentric movement of the bars, a pair of bars with onefrom each set in cooperative article supporting relation on oppositesides of the center of mass of an article supported on the bars, saidmeans for supporting the bars including a pair of regular polygonallyshaped axles disposed spaced apart longitudinally of the bars and eachhaving the same number of faces as the number of bars in each set andwith the number of bar faces being at least six in number, a pluralityof identical bar supporting discs with one for each bar, said discshaving corresponding off-center polygonal apertures sized to slidablyfit in driven relation on the polygonal axles and with the discsreceived thereon in angularly spaced relation in accordance with theangular spacing of the faces of the axles, each bar mounted on one ofthe discs on each axle to be driven in eccentric movement as aforesaidupon rotation of the axles, and means connected to one of the axles forrotating the same and thereby driving the bars.
 2. The invention asdefined by claim 1 wherein there is a polygonal axle for each set withthe number of sides of the polygon being a function of the number ofbars in the set, and the axles of the pair of sets are end connected inangular offset relation equal to one-half the angle between the sides ofthe polygonal shape of the axles.
 3. In a conveyor as defined in claim 1where the means for driving the bars is connected to both sets of bars.4. A conveyor as defined in claim 1 wherein the means for supporting thebars comprises a pair of axles for each set and eccentrics thereonsupporting the bars, and the means for driving the bars is connectedonly to one of the axles of each set.
 5. A conveyor as defined in claim1 wherein the eccentric discs have a thickness greater than thethickness of the bars and each of the bars in a set being in closeproximity and having their eccentric discs touching to provide clearancebetween adjacent bars.